1. Field
Apparatuses and methods consistent with exemplary embodiments relate to an infrared transmission shutter, and more particularly, to an infrared transmission shutter formed on a large area and a method of manufacturing the same.
2. Description of the Related Art
To realize a three-dimensional (3D) image obtaining apparatus, such as a 3D camera, a means for measuring distances from multiple points on an object's surface is required. To obtain accurate distance information with respect to the object, a Time-of-Flight (TOF) method has been introduced. A phase delay measurement method, which is one of a number of TOF methods, uses external modulation to obtain a high-resolution distance image. To perform the external modulation, a GaAs semiconductor-based transmission optical shutter, which is easy to manufacture, has a compact size, and can be driven with a low voltage, has been recently proposed.
The GaAs semiconductor-based transmission shutter is disposed in front of a charge-coupled device (CCD) sensor to modulate light input to the sensor. The GaAs semiconductor-based transmission shutter has a simple structure and can be miniaturized, and thus, the GaAs semiconductor-based transmission shutter can be easily applied to a 3D camera.
The transmission shutter has multiple quantum wells (MQW) disposed between a p-type electrode and an n-type electrode and uses a phenomenon in which when a reverse bias voltage is applied to both the p-type and n-type electrodes, light is absorbed by the MQW. The GaAs semiconductor-based transmission shutter can be driven at a high speed, and its driving voltage is low, and a reflectivity difference between ON and OFF, that is, a contrast ratio, is high.
When the GaAs semiconductor-based transmission shutter is manufactured on a large area, because a GaAs substrate used as an epitaxial growth substrate is opaque with respect to infrared rays, removal of the GaAs substrate on a light transmission region is necessary, thereby making the optical shutter fragile.